Security systems are used widely around the world in both commercial and residential settings. Most systems register alarm signals both locally and at central monitoring stations, commonly located within the same city or region. The central monitoring stations may be either local law enforcement or private services, which usually notify the police force. Commonly, an alarm is triggered and the security system activates a local warning and seizes a conventional telephone line to notify the central monitoring station of the situation.
Many of these security systems employ cellular backups in addition to common ground line communications when alarms are triggered. These backup are attractive, since conventional telephone lines are subject to being severed during unauthorized activity (e.g., burglary). Should no telephone line be available, the system switches to the cellular backup to establish a cellular link with the monitoring station to report the alarm. Alternatively, some systems establish concurrent conventional telephone links and cellular phone links with the central monitoring station. The cellular backups are essentially commercially available cellular telephones that request and receive high quality wireless voice communication channels.
As common as these backups have become, they do possess limitations which restrict their economic viability. One limitation associated with present cellular backup systems is that communications are limited to one-way outgoing messages. Such systems do not posses the ability to contact the backups independently because the backups are not able to receive messages from outside sources. As previously stated, when an event-driven alarm occurs, the system establishes a cellular link with the associated central monitoring station and transmits an alarm signal. If the security system develops a problem that does not trigger an alarm signal (e.g., loss of power, sensor failure or internal circuitry failure), no alarm signal is transmitted and the central monitoring station cannot establish a link to the alarm system to verify system status.
Another limitation commonly encountered when employing present cellular backup systems is the large bandwidth required to transmit a relatively small alarm signal. Conventional cellular backup systems must utilize the same baud rates and bandwidths as commercially available personal cellular communication systems (commonly telephones). Commercial cellular lines are designed for voice and video transmissions (continuous media) and therefore require large bandwidths and baud rates with little or no interruptions to support a desired quality of service. Customers using security systems with cellular backups are required to pay for high quality, continuous media cellular services where systems with smaller bandwidths could suffice.
In an attempt to solve this problem, designers of more recent systems considered using cellular digital packet data (CDPD) technology to overcome the problems with bandwidth usage. CDPD may be broadly described as a new process for cellular use as a means of data transmission. Through CDPD technology, data packets are sent along idle channels of existing cellular voice networks. Further, these packets may be sent at very high speeds during pauses in cellular phone conversations. By adding CDPD to an existing cellular system, cellular operators can transmit data at much high speeds without seeking out separate data transmission lines.
Unfortunately, CDPD has many drawbacks which make it unattractive as a solution to the problems encountered. Although this technology is able to utilize in-band “spaces” in cellular traffic, even during peak usage times, large bandwidth are still required for the transmissions. Further, where in-band traffic “spaces” are not available, CDPD seizes a full cellular channel, thus subjecting the user to the inefficiencies encountered while employing full bandwidth, commercial cellular lines.
Finally, power supplies and battery backups are another concern encountered while employing conventional cellular backups. Using and maintaining cellular backups require expensive power supplies and battery backups which further economically burden the user. Since commercial cellular systems require continuous transmission with little or no interruptions, maintaining system power is important. Since security systems transmit such small amounts of data, using commercial quality cellular lines amount to significant overkill and the associated power systems contribute to cost inefficiencies.
Accordingly, what is needed in the art is an improved alarm system that overcomes the above-described deficiencies of the prior art.